Safety device for elevators



able fastenin -nuts, e' and I UNTED STATES PATENT OFFICE@ suMNER SHAW, OF BOSTON, MASSACHUSETTS.

SAFETY DEV ICE FOR ELEVATORS.

SPECIFICATION forming part of Letters Patent No. 240,193, dated Aprl 12, 1881. I Application filed February 5, 1881. (No model.)

To all whom 'it may concw:

Be it known that I, SUMNER SHAW, a citizen of the United States, residing at Boston, in the County of Suft'olk and State of Massachusetts, have invented certain new and useful Improvements in Safety Devices for Elevators; and I do hereby declare that the sane are fully described in the following speeification and illustrated in the accompanying drawngs.

This invention relates to improvements in safety devices for elevators, and it is carried out as follows, reference being had to the aecompanying drawings, in which Figure 1 represents a plan View, and Fig. 2 rcpresents a longitudinal section on the line A B, shown in-Fig. l.

Similar letters refer to similar parts wherever they occur on the difierent parts of the drawings'.

In the (lrawings, a represents the eleVator-z well.

I is the car, actuated by means of the wire rope c, which is carried over the wheel or pulley d, as usual.

e represents an upper beam at the top ot' the well a, and frepresents a similar beam at its bottom, as usual.

b' is the top of the car b, and b" represents the bottom or floor of said ear.

From top to bottom of the well a extends a spirally-grooved stationary cylinder, g, provided with a circumferential spiral groove, g', as shown. I prefer to make said spirally-grooved cylinder g hollow and in section, as shown, and each section being made with a projection to fit into a corresponding recess on the next section, as shown atg' in Fg. 2, so as to prevent a rotary motion of any sectional part of the spirally-grooved eylinder g during the up-anddown motion of the car b, as will be further described.

his a central rod within the hollow cylinderg, which maybe made also in sections, united together by screw or other equivalent eonplings, as may be desired. The upper and lower ends of the central rod, h, pass respectively through the upper and lower beams, e and f, to which it is secured by means of suitas shown, by which arrangement the various hollow sections composing the spirally-grooved cylinder g are held rigidly together, so as to form, as it were, one solid piece. The spirally-grooved cylinder g passes through the ear I), as shown, perforations being for this purpose made through the top and floor thereof, as shown, the floor-perforation being made large enough to allow the hub of the nut k to be inserted through it without coming in contact with the side of such perforation. The nut k is also spirally grooved and provided with a spiral projection, Ic', fitting nicely into the corresponding spiral groove g' on the cylinder g, as shown in Fig. 2.

k" is a flange at the lower end of the nut k, and k' is a similar flange at the upper end of said nut.

l is an annular flange Secured to the top of the floor b", and Z' is a similar annular flange Secured to the bottom or under side of the said floor b", as shown.

The pitch of the spiral groove g' is so made that it will cause the nut k to rotate freely around the spiral cylinder g Without much frietion during the ordinary up-and-down motion of the carb but in case of an accident, by the breaking of the rope or otherwise, the flange l' is brought in contact with the lower flange, Ic", of the nut k, causing the whole weight of the car b to rest on the said nut, by which the car is instantly brought to a standstill, as the nut k is prevented from turning around the spirally-grooved cylinder g on account of the inereased frictional resistance between the lower flange, k", on the nut k and the lower flange, l', on the under side of the floor b".

I am aware of United States Patent No. 87,143, of l869,in which a positively-actuated nut is eaused to rotate around a stationary serew-shaft, so as to raise and lower the ele- Vator-car; but such is not my invention, as

. my nut is not positively actuated to raise and lower the car, but only loosely rotated around the screshaft by the vertical motion of the car, and serving only as a safety deviceif the ear should, from any cause, descend too rapidly, the car in my invention being raised and lowered by an independent hoisting device. I also wish to state that I do not claim a continuous sectional screw-shaft, as shown in said Letters Patent; neither do I claim the partic- IOO ular kind of nut as shown in United States nation with an independent hoisting device, [O

Letters Patent No. 119,'7 31, of 1871; but as and for the purpose set forth.

What I wish to secure by Letters Patent, In testimony whereof I have affiXed my sigand claim, is nature in presence of two witnesses.

The berem-described safety device for eleva-tors, consisting of the stationa'y sprallygrooved eylinder g g', the loosely-rotatng nut Witnesses 70, having upper and lower flanges, 79' k", and ALBAN ANDRN, the flanges l l' on the car-floor b", in combi- HENRY CHADBOURN.

SUMNER SHAW. 

